Heavy duty vehicles such as, but not limited to, semi trailer trucks generally include a tractor unit having an engine, a cabin and a control system for the vehicle and a trailer unit connected to the tractor unit. The trailer unit may embody electrical units which are electrically coupled with the control system of the vehicle. The electrical unit typically includes a coupling having a plug element and a socket element that are mechanically coupled for providing electric coupling to the trailer unit. The plug element is made to connect with an electrical cable extending from the control system of the vehicle. The socket element of the coupling is generally attached to the trailer unit.
One known way of mechanically coupling the plug element with the socket element is provided using a spring and a ratchet mechanism. In this mechanical coupling, the socket element is provided with a hinged cap tensioned with a spring and a ratchet on the cap. Once the plug element is inserted, the hinged cap tensioned by the spring forces the cap to close and thus the ratchet mechanically couples the plug element with the socket element. Though the spring and the ratchet holds the plug element with the socket element, the coupling between the plug element and the socket element can weaken over time causing disengagement of the plug element from the socket element. Thus, the electrical connection between the trailer unit and the control system of the vehicle is also disconnected.
In view of one or more problems stated above, there is a need for an improved restraining mechanism for continuous engagement of the plug element with the socket element.